State looks to fungicide to protect the potato crop

AUGUSTA — Much of the state’s seed potato supply for this year is infected with blight, and the state has asked the federal government for an emergency exemption to make an effective but expensive toxic seed treatment available to farmers.

“The time is pretty germane to have it now,” said Steve Johnson, a crops specialist with the University of Maine cooperative extension. “The pathogen has been found in seeds, and so the last thing we want to do is start our own epidemic by planting these seeds.”

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Extreme wet weather and infected seed potatoes that were imported during the 2011 growing season resulted in a severe outbreak of late blight on Maine’s potato crop. Saturated soil late in the season transferred it to the tubers in the ground, Johnson said.

To ward against another severe outbreak of late blight on Maine’s potato crop, the Board of Pesticides Control has asked the federal government for an emergency exemption registration for the fungicide Revus, an expensive fungicide that’s mildly to highly toxic to different species.

Revus is new on the market and is registered for blight control in the U.S. for grapes and vegetables, including potatoes, but not for seed potato pieces, according to the U.S. Environmental Protection Agency.

Johnson said Revus is an effective plant health medicine on the path to becoming a fully registered material, but not in time for this year’s potato growing season.

If the exemption is granted, farmers will weigh the high cost of the fungicide – $350 a gallon – against the money they could lose if blight ruined their crop.

Bruce Flewelling, a potato grower in Easton, said it will cost about $20,000 to use Revus to treat seeds on his 1,000-acre farm.

“I’m looking at using it. I’m excited to use it, but then I looked at the price tag,” Flewelling said. “There again, if we do get blight, everything goes out the window. If we can keep it out (of our crop), it’s better for me and my budget. Last year it was a nightmare. We had a rough time with the wet weather.”

Flewelling said Revus is a good chemical that he has sprayed over the top of his potato plants over the past four years, but never on seed pieces.

“It’s a big area, so we would use it on all the seed we got,” he said.

Paul Schlein, spokesman for the Maine Board of Pesticides Control, said Maine has about 56,000 acres of potatoes. An average farm is about 190 acres. He said it would cost a potato grower using Revus between $15 and $30 an acre depending on the potato variety.

Johnson said it could cost farmers $3,000 per acre if blight hits their crops. He said potato farmers suffered tremendous losses last year because of the blight. On top of the unprecedented rain, Tropical Storm Irene spread the epidemic to other fields.

The state board unanimously approved the request and sent it on to the EPA for consideration, which has 50 days to make a decision, Johnson said.

“They approved this material in Montana, so it isn’t unprecedented,” he said. “They will let us know within 50 days, which is a little bit too long.” He said the treatment has to be done before planting and ideally, the seed would be treated in April for May planting.

He added that the federal government is aware of the time crunch, so it may act fast.

“That’s a serious loss,” he said. “This is trying to control and manage the disease.”

Rob Johanson, a certified organic grower in Dresden, said he will treat his potato seeds this year with biological inoculates to protect them from blight.

“It’s the only thing we got going to protect the plants in an organic system. We don’t have chemicals like the other guys,” he said.

Revus contains the active ingredient mandipropamid. According to a 2008 California Department of Pesticide Regulation Public Report, mandipropamid is slightly toxic to birds and honeybees, moderately toxic to fish and some shrimp, and highly toxic to the Eastern oyster.

Denis Thoet, who grows potatoes on his small West Gardiner farm each year for his community-supported agriculture customers, said he would never pre-treat anything with chemicals.

He said the use of a fungicide such as Revus benefits only large-scale potato farms in Maine.

“It’s not good for you and probably not good for the plant,” Thoet said. “There’s other ways to control blight. Our crop was affected in 2009. That’s the first year blight was a factor in small farms; it’s always a factor in large farms.

“They treat it on a large scale and have a large-scale problem with seed. They’re putting (chemicals) in the ground, and the consequences are worse than they think.”

Growers who sell more than $1,000 of plant products intended for human consumption and use over-the-counter pesticides must get an applicator license, which is good for three years and requires passing an exam.

Kennebec Journal Staff Writer Mechele Cooper can be contacted at 621-5663 or at:

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